Replacing the grids in your diatomacious earth filter can be a difficult task. The 8 grids ( 7 large and 1 small)  are difficult to arrange under the manifold. The average life of a d.e. grid is approx. 6 years. If you are only replacing one damaged grid, stop reading. If you are replacing the entire set you may want to consider buying the entire insert. It will include the grid locator, air relief, manifold, and all new grids. You will simply lift out old internals and set in new internal. The Above Ground Pool & Spa Company stocks the complete internal and also each separate part. Parts are also available at www.waterwayparts.com